Category Archives: nuts

A great thing about the macadamia nut is that it’s one of the few nuts with a good omega-6/omega-3 fatty acid ratio. In other words, it’s high in omega-3 and low in 6. This may have important cardiovascular health implications. Macadamias are one of the nuts I recommend in the Low-Carb Mediterranean Diet and Paleobetic Diet.

David writes:

The first Australian macadamia plantation didn’t begin until the 1880s. And not until 1954 with the introduction of mechanised processing did commercial production became viable. Nowadays about 90 percent of the the world’s macadamia nut production comes from Hawaii, where it has become its third most important crop, according to The Wellness Encyclopedia of Food and Nutrition, University of California at Berkeley (1992).

Read the rest, where you’ll learn that macadamia nuts are the highest of all nuts in calories, gram for gram.

In the largest study of its kind, Harvard scientists found that people who ate a handful of nuts every day were 20% less likely to die from any cause over a 30-year period than those who didn’t consume nuts. The study also found that regular nut-eaters were leaner than those who didn’t eat nuts, a finding that should calm any fears that eating nuts will make you gain weight.

The report also looked at the protective effect on specific causes of death. “The most obvious benefit was a reduction of 29% in deaths from heart disease—the major killer of people in America,” according to Charles S. Fuchs, director of the Gastrointestinal Cancer Treatment Center at Dana-Farber, the senior author of the report and a professor of medicine at Harvard Medical School. “But we also saw a significant reduction—11% —in the risk of dying from cancer,” added Fuchs.

Walnuts seem to have the lowest omega-6/omega-3 fatty acid ratio of all the common nuts. That may make them the healthiest nut. The jury is still out. Macadamia nuts also have a good ratio. Paleo dieters focus on cutting out omega-6s and increasing omega-3s. Julianne Taylor has a great post on how to do that with a variety of foods, not just nuts.

Background Epidemiological studies have consistently associated nut consumption with reduced risk for coronary heart disease. Subsequently, many dietary intervention trials investigated the effects of nut consumption on blood lipid levels. The objectives of this study were to estimate the effects of nut consumption on blood lipid levels and to examine whether different factors modify the effects.

Methods: We pooled individual primary data from 25 nut consumption trials conducted in 7 countries among 583 men and women with normolipidemia and hypercholesterolemia who were not taking lipid-lowering medications. In a pooled analysis, we used mixed linear models to assess the effects of nut consumption and the potential interactions.

Results: With a mean daily consumption of 67 g of nuts [about 2 ounces or 2 palms-ful], the following estimated mean reductions were achieved: total cholesterol concentration (10.9 mg/dL [5.1% change]), low-density lipoprotein cholesterol concentration (LDL-C) (10.2 mg/dL [7.4% change]), ratio of LDL-C to high-density lipoprotein cholesterol concentration (HDL-C) (0.22 [8.3% change]), and ratio of total cholesterol concentration to HDL-C (0.24 [5.6% change]) (P < .001 for all) (to convert all cholesterol concentrations to millimoles per liter, multiply by 0.0259). Triglyceride levels were reduced by 20.6 mg/dL (10.2%) in subjects with blood triglyceride levels of at least 150 mg/dL (P < .05) but not in those with lower levels (to convert triglyceride level to millimoles per liter, multiply by 0.0113). The effects of nut consumption were dose related, and different types of nuts had similar effects on blood lipid levels. The effects of nut consumption were significantly modified by LDL-C, body mass index, and diet type: the lipid-lowering effects of nut consumption were greatest among subjects with high baseline LDL-C and with low body mass index and among those consuming Western diets.

“What about that recent study in American Journal of Clinical Nutrition…?”

As much as possible, I base my nutrition and medical recommendations on science-based research published in the medical literature. Medical textbooks can be very helpful, but they aren’t as up-to-date as the medical journals.

In the early 2000s, a flurry of research reports demonstrated that very-low-carb eating (as in Dr. Atkins New Diet Revolution) was safe and effective for short-term weight management and control of diabetes. I was still concerned back then about the long-term safety of the high fat content of Atkins. But 80 hours of literature review in 2009 allowed me to embrace low-carbohydrate eating as a logical and viable option for many of my patients. The evidence convinced me that the high fat content (saturated or otherwise) of many low-carb diets was little to worry about over the long run.

By the way, have you noticed some of the celebrities jumping on the low-carb weight-management bandwagon lately? Sharon Osbourne, Drew Carey, and Alec Baldwin, to name a few.

My primary nutrition interests are low-carb eating, the Mediterranean diet, and the paleo diet. I’m careful to stay up-to-date with the pertinent scientific research. I’d like to share with you some of the pertinent research findings of the last few years.

Dietary fat, including saturated fat, is not a cause of vascular disease such as heart attacks and atherosclerosis (hardening of the arteries). (Multiple research reports.)

If you’re overweight and replace two sugary drinks a day with diet soda or water, you’ll lose about four pounds over the next six months. (American Journal of Clinical Nutrition, 2012.)

United States residents obtain 40% of total calories from grains and added sugars. Most developed countries are similar. Dr. Stephan Guyenet notes that U.S. sugar consumption increased steadily “…from 6.3 pounds [2.9 kg] per person per year in 1822 to 107.7 pounds [50 kg] per person in 1999. Wrap your brain around this: in 1822 we ate the amount of added sugar in one 12-ounce can of soda every five days, while today we eat that much sugar every seven hours.”

A very-low-carb diet improves the memory of those with age-related mild cognitive impairment. Mild cognitive impairment is a precursor to dementia. (University of Cincinnati, 2012.)

High-carbohydrate and sugar-rich diets greatly raise the risk of mild cognitive impairment in the elderly. (Mayo Clinic study published in the Journal of Alzheimers’ Disease, 2012.)

One criticism of low-carb diets is that they may be high in protein, which in turn may cause bone thinning (osteoporosis). A 2010 study shows this is not a problem, at least in women. Men were not studied. (American Journal of Clinical Nutrition.)

Obesity in U.S. children tripled from 1980 to 2000, rising to 17% of all children. A low-carb, high-protein diet is safe and effective for obese adolescents. (American Journal of Clinical Nutrition, 2010.)

Mediterranean Diet

The traditional Mediterranean diet is well established as a healthy way of eating despite being relatively high in carbohydrate: 50 to 60% of total calories. It’s known to prolong life span while reducing rates of heart disease, cancer, strokes, diabetes, and dementia. The Mediterranean diet is rich in fresh fruits, vegetables, nuts and seeds, olive oil, whole grain bread, fish, and judicious amounts of wine, while incorporating relatively little meat. It deserves your serious consideration. I keep abreast of the latest scientific literature on this diet.

The Mediterranean diet reduces risk of sudden cardiac death in women. (Journal of the American Medical Association, 2011.)

The Mediterranean diet is linked to fewer strokes visible by MRI scanning. (Annals of Neurology, 2011.)

It reduces the symptoms of asthma in children. (Journal of the American Dietetic Association, 2011.)

Compared to low-fat eating, it reduces the incidence of type 2 diabetes by 50% in middle-aged and older folks. (Diabetes Care, 2010.)

A review of all available well-designed studies on the Mediterranean diet confirms that it reduces risk of death, decreases heart disease, and reduces rates of cancer, dementia, Parkinson’s disease, stroke, and mild cognitive impairment. (American Journal of Clinical Nutrition, 2010.)

It reduces the risk of breast cancer. (American Journal of Clinical Nutrition, 2010.)

Clearly, low-carb and Mediterranean-style eating have much to recommend them. Low-carb eating is particularly useful for weight loss and management, and control of diabetes, prediabetes, and metabolic syndrome. Long-term health effects of low-carb eating are less well established. That’s where the Mediterranean diet shines. That’s why I ask many of my patients to combine both approaches: low-carb and Mediterranean. Note that several components of the Mediterranean diet are inherently low-carb: olive oil, nuts and seeds, fish, some wines, and many fruits and vegetables. These items easily fit into a low-carb lifestyle and may yield the long-term health benefits of the Mediterranean diet. If you’re interested, I’ve posted on the Internet a Low-Carb Mediterranean Diet that will get you started.

Disclaimer: All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status. Always consult your personal physician before making any dietary or exercise changes.

Canadian researchers randomized 117 type 2 diabetics to eat their usual types of food, but also to be sure to eat either

mixed nuts (about 2 ounces a day)

muffins (I figure one a day)

or half portions of each.

They did this daily for three months. Compared to the muffin group, the full nut group ate quite a bit more monounsaturated fatty acids. (I don’t have full study details because I have access only to the article abstract.)

Results

Hemoglobin A1c, a reliable measure of blood sugar control, fell by 0.21% in the mixed nut group. That’s a move in the right direction. LDL cholesterol, the “bad cholesterol” linked to heart and vascular disease, also dropped significantly.

So What?

The investigators suggest that replacement of certain carbohydrates with 2 ounces of daily mixed nuts is good for people with type 2 diabetes.

Investigators at the University of Lund found enrolled 38 male heart patients—average age 61—patients and randomized them to either a paleo diet or a “consensus” (Mediterranean-like) diet to be followed for 12 weeks. Average weight was 94 kg. Nine participants dropped out before completing the study, so results are based on 29 participants. All subjects had either prediabetes or type 2 diabetes (the majority) but none were taking medications to lower blood sugar. Baseline hemoglobin A1c’s were around 4.8%. Average fasting blood sugar was 125 mg/dl (6.9 mmol/l); average sugar two hours after 75 g of oral glucose was 160 mg/dl (8.9 mmol/l).

The paleo diet was based on lean meat, fish, fruits, leafy and cruciferous vegetables, root vegetables (potatoes limited to two or fewer medium-sized per day), eggs, and nuts (no grains, rice, dairy products, salt, or refined fats and sugar).

The paleo group ate significantly more nuts, fruit, and vegetables. The Mediterranean group ate significantly more cereal grains,oil, margarine, and dairy products.

Glucose control improved by 26% in the paleo group compared to 7% in the consensus group. The improvement was statisically significant only in the paleo group. The researchers believe the improvement was independent of energy consumption, glycemic load, and dietary carb/protein/fat percentages.

Hemoglobin A1c’s did not change or differ significantly between the groups.

Neither group showed a change in insulin sensitivity (HOMA-IR method).

Comments

The authors’ bottom line:

In conclusion, we found marked improvement of glucose tolerance in ischemic heart disease patients with increased blood glucose or diabetes after advice to follow a Palaeolithic [sic] diet compared with a healthy Western diet. The larger improvement of glucose tolerance in the Palaeolithic group was independent of energy intake and macronutrient composition, which suggests that avoiding Western foods is more important than counting calories, fat, carbohydrate or protein. The study adds to the notion that healthy diets based on whole-grain cereals and low-fat dairy products are only the second best choice in the prevention and treatment of type 2 diabetes.

This was a small study; I consider it a promising pilot. Results apply to men only, and perhaps only to Swedish men. I have no reason to think they wouldn’t apply to women, too. Who knows about other ethnic groups?

This study and the one I mention below are the only two studies I’ve seen that look at the paleo diet as applied to human diabetics. If you know of others, please mention in the Comments section.

The higher fruit consumption of the paleo group didn’t adversely affect glucose control, which is surprising. Fruit is supposed to raise blood sugar. At 493 grams a day, men in the paleo group ate almost seven times the average fruit intake of Swedish men (75 g/day). Perhaps lack of adverse effect on glucose control here reflects that these diabetics and prediabetics were mild cases early in the course of the condition—diabetes tends to worsen over time.

Present day paleo and low-carb advocates share a degree of simpatico, mostly because of carbohydrate restriction—at least to some degree—by paleo dieters. Both groups favor natural, relatively unprocessed foods. Note that the average American eats 250-300 g of carbohydrates a day. Total carb intake in the paleo group was 134 g (40% of calories) versus 231 g (55% of calories) in the Mediterranean-style diet. Other versions of the paleo diet will yield different numbers, as will individual choices for various fruits and vegetables. Forty percent of total energy consumption from carbs barely qualifies as low-carb.

Study participants were mild, diet-controlled diabetics or prediabetics, not representative of the overall diabetic population, most of whom take drugs for it and have much higher hemoglobin A1c’s.

Lindeberg and associates in 2009 published results of a paleo diet versus standard diabetic diet trial in 13 diabetics. Although a small trial (13 subjects, crossover design), it suggested advantages to the paleo diet in terms of heart disease risk factors and improved hemoglobin A1c. Most participants were on glucose lowering drugs; none were on insulin. Glucose levels were under fairly good control at the outset. Compared to the standard diabetic diet, the Paleo diet yielded lower hemoglobin A1c’s (0.4% lower—absolute difference), lower trigylcerides, lower diastolic blood pressure, lower weight, lower body mass index, lower waist circumference, lower total energy (caloric) intake, and higher HDL cholesterol. Glucose tolerance was the same for both diets. Fasting blood sugars tended to decrease more on the Paleo diet, but did not reach statistical significance (p=0.08).

The paleo diet shows promise as a treatment or preventative for prediabetes and type 2 diabetes. Only time will tell if it’s better than a low-carb Mediterranean diet or other low-carb diets.

Links

“Do not be deceived: God cannot be mocked. A man reaps what he sows. Whoever sows to please their flesh, from the flesh will reap destruction; whoever sows to please the Spirit, from the Spirit will reap eternal life.”